Schneider TM221 clear MW addresses

Hey all, here's a simple question, I am writing to a range of MW addresses %MW103 to %MW194, I want to clear all of these to a value of 0 with a bit from the HMI.
I have the following:
%MW4:=91

%MW103[%MW4]:=0

But this doesn't seem to be working, any thought. I know it's simple, but I come from the structured text world and getting my syntax correct can be difficult.

you are using indexed object, and writing zero to address %MW103+91 = %MW194

Command what you are looking for is %MW103:91:=0

p.s search tables from help files)

Thanks again Lare.